Field of the Invention
The present invention relates to a coating apparatus, an imprint apparatus, and a method of manufacturing an article.
Description of the Related Art
There are microfabrication technologies for forming a pattern to an imprint material on a substrate using a mold. These technologies are also called imprint technologies in which a nanoscale pattern (structure) can be formed on a substrate. For example, one of the imprint technologies is a photocuring method. In imprint apparatuses employing the photocuring method, first, a photocuring resin acting as an imprint material is supplied to a shot region on a substrate. Next, the imprint material on the substrate is molded using a mold. Then, after light is applied to cure the imprint material, the mold is released, and thereby a pattern of the imprint material is formed on the substrate. In addition to the photocuring method, the imprint technologies include, for instance, a thermosetting method of curing an imprint material using heat.
The imprint material is supplied to (coated on) the shot region on the substrate by a dispenser. This dispenser serves as a component of a coating apparatus, and discharges the imprint material in the form of a liquid according to, for instance, an inkjet method. A configuration of the dispenser is similar to that of an ink jet head that is generally used in an ink jet printer. Here, when the material such as the imprint material is attached to a discharge surface of the ink jet head, this may cause a decrease in discharge performance (e.g., a decrease in discharge position accuracy or stability or clogging of a discharge opening). Therefore, an ink jet recorder is disclosed in Japanese Patent Laid-Open No. H07-60954, in which electric wiring is provided around a discharge opening, and a variation in resistance value when ink is attached to the electric wiring is measured, thereby previously detecting leakage of the ink. Also, an ink jet recording device is disclosed in Japanese Patent Laid-Open No. H07-246708 in which light is applied to and reflected from a discharge surface, and an intensity of the reflected light is measured by an optical sensor, thereby previously detecting leakage of ink.
However, in the techniques disclosed in Japanese Patent Laid-Open Nos. H07-60954 and H07-246708, it is possible to detect abnormality of the discharge surface, i.e. whether the discharged material such as the liquid is not attached to the discharge surface, but it is difficult to specifically measure a thickness of the liquid attached to the discharge surface. This implies that it is difficult to determine whether to perform maintenance according to a degree of, for instance, the material attached to the discharge surface. Therefore, in all cases in which the material such as the liquid is attached to the discharge surface, if the maintenance is performed with no exception without the above determination, the maintenance may be performed even when no influence would be exerted on a discharge operation of discharging the liquid even if the maintenance were not actually performed. Such undue maintenance is not favorable because it leads to an increase in maintenance time (a decrease in operable time for an imprint operation) as well as damage to the discharge surface caused by the maintenance.